LM2676: Difference between Webench designer and datasheet.

Cyril Dufoing

Part Number: LM2676

Hello,

I tried for the first time webench designer to design a DC-DC buck converter with LM2676. However the design is not following the design requirement in the datasheet. I was wondering if we could follow the webench designer without any doubt on its fiability ?

Regards,

Cyril

over 8 years ago

0 Frank De Stasi over 8 years ago

TI__Guru 73175 points

Please give more details of the schematics and what is different between the two designs.

0 Cyril Dufoing over 8 years ago in reply to Frank De Stasi

Prodigy 40 points

The principal difference is the input and the output capacitors. In webench designer : 1*100uF as output and 1*4.7uF as input capa.

In the datasheet : 2*100uF as output and 3*4.7uF as input. Then, the datasheet don't speak about a 100nF in parallel with the input capacitors.

0 Frank De Stasi over 8 years ago in reply to Cyril Dufoing

TI__Guru 73175 points

The difference in the input capacitors is not too significant. You can use more Cin if you have long lines from

your input supply to the regulator. The 100nF is always a good idea to provide high frequency decoupling at the input.

The device should be stable with either of the output capacitor banks that you mentioned. More output cap will give

slower transient response, but less overshoot/undershoot in the output during a load transient.

0 Cyril Dufoing over 8 years ago in reply to Frank De Stasi

Prodigy 40 points

Ok thank you. I followed the webench and my prototype is not working. I think that it is the layout which is not optimized for smps. Thank you.

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LM2676: Difference between Webench designer and datasheet.